1. Technical Field
The present invention relates to a pattern forming apparatus used in a light guide panel for backlight of a liquid crystal display device, a keypad, a telephone, a lighting surface light source, etc. More particularly, the present invention relates to a pattern forming apparatus for forming a light guide pattern, by splitting a laser beam into several beams to generate a plurality of concentrated laser beams and scanning with the laser beams using a stage movable front and rear, a movement unit movable left and right, and a header unit coupled to the movement unit.
2. Description of the Related Art
Commonly, a light guide panel, which is a plate for providing a path for uniformly scattering and diffusing light scanned from a light source, is being applied to a light receiving flat display device such as a liquid crystal display device, or a surface light source device used in a lighting signboard, etc.
FIG. 1 is a cross section schematically illustrating a conventional surface light source device.
Referring to FIG. 1, the conventional surface light source device 10 includes a light guide panel 11, a reflective sheet 12 installed below the light guide panel 11, a light source 13 installed at one side of the light guide panel 11, and a cover member 14 covering the light source 13. As the light source 13, a cold cathode fluorescent lamp, a Light Emitting Diode (LED), etc. can be used. In the light guide panel 11, a plurality of light guide patterns 15 are formed by using a bead-shaped Oxide Titanium (TiO2) and ink including glass, acryl, etc. to scatter and diffuse light incident on one surface of a transparent acrylic resin. In the surface light source device 10, light irradiated from the light source 13 is incident on the light guide panel 11, and the incidence light is guided through the light guide panel 11 as indicated by arrows. After that, the guided light is reflected at relatively uniform illumination in each part by the reflective sheet 12 and the light guide patterns 15. After that, the reflected light passes through a diffuse sheet 16 and again passes through a prism sheet 17 to direct toward the front.
However, the light guide patterns 15 formed in a printing method have the following problems.
A process of manufacturing and printing an ink for forming light guide patterns is very complex, and an error rate of omitting or staining a part of a printed part, etc. is high. Due to this, a throughput for the light guide pattern is low to the extent of about 80% to 90%. Also, there is a disadvantage that the light guide panel based on the printing method is not environment-friendly because recycling is difficult.
Particularly, the light guide patterns 15 are based on a method using a light reflection of a print ink itself, so a light absorption phenomenon of the ink itself occurs necessarily. This light absorption phenomenon results in a decrease of a light efficiency of a surface light source device.
As a solution to the above problem, a non-printing method is applied. The non-printing method can be an injection molding method using a mold.
The aforementioned method has to repeat a mold revision work more than a few dozens of times. Thus, there is a disadvantage of increasing a development cost. Also, as a period of time of mold manufacturing is lengthened, it is difficult to meet a suddenly changing requirement for development of a product model. Also, there is a problem that, in case that a product gets thick, this causes an increase of a period of time of cooling after injection to a few minutes or so, thus decreasing productivity. Inversely, in case that a product gets very thin and gets wide in area, an error of pattern non-formation, etc. takes place because of imperfect injection.
A solution to the above problems is a method of processing a light guide pattern using a laser. The use of the laser makes a constant treatment to a desired dimension possible with no influence from a deviation of a thickness of material, and makes a supplementary device such as a mold, a mask, etc. unnecessary. Also, the pattern is recyclable and environment-friendly because they are not coated with separate materials. However, because the conventional method has to form all the patterns one by one through a laser treatment, there is a problem that a period of time of treatment greatly increases and thus, productivity decreases.